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Comment bien choisir son poste à souder MIG ?
Whether you are a beginner, hobbyist, occasional DIYer, or professional welder, choosing a semi-automatic welding machine can be a real challenge.
First, it is often difficult to understand how the MIG/MAG process (135 for experts) will help you achieve what you want.
Second, there are numerous manufacturers and models, with opinions that are not always well-argued... In short, it can be confusing!
Finally, the equipment and process require consumables, repairs, and tips to fully utilize their potential... So, for all these reasons and to help you see clearly, we have decided to guide you through a few steps.
Step 1: What is the MIG/MAG process, and what are its advantages and disadvantages?
Welding, commonly referred to as semi-automatic or MIG/MAG (GMAW in English), involves creating an electric arc between the base metal and the welding wire, which is fed semi-automatically by the welding machine.
This arc melts the base metal and the filler wire, creating a molten pool called the weld pool. During this phase, which occurs in a few milliseconds, the steel molecules mix to form a solidified weld. The weld pool is protected from oxidation by an inert gas (Argon or a mix of Argon/CO2).
To achieve a successful weld, which means good penetration between the filler wire and the base material, four conditions must be met:
- The welding wire must have mechanical and chemical properties compatible with the material being welded.
- The shielding gas should be Argon/CO2 (for steel and stainless steel) or Argon (for aluminum).
- The welding parameters, such as current (A) and wire feed speed, must be adjusted to ensure proper wire fusion and good weld penetration.
- The preparation of the pieces to be welded should include light grinding of the welding area and the preparation of a bevel if necessary.
The advantages of the MIG/MAG process are numerous:
- Productivity: The automatic wire feed allows for high welding and deposition rates, suitable for long runs, series production, sheet metal work, structural components, and part repair.
- Appearance: The wire diameter ranges from 0.8 to 1.6 mm, allowing for welding materials with thicknesses from 1 to 30 mm with a consistent bead size. It is much easier to achieve a good appearance compared to the stick electrode process.
- Ease of Learning: According to many, this is the simplest process to learn. The technique is quickly acquired, while adjusting the welding parameters requires a bit more perseverance.
The INVERTER welding technology is widely used by manufacturers. This power electronics, combined with the latest generation of welding curves, is found in welding brands such as FRONIUS, EWM, and KEMPPI. This greatly simplifies the user’s life; the settings are easier, and the quality and stability of the arc are optimal for a very satisfying result.
Step 2: What types of pieces should I weld and under what conditions?
Types of Pieces to Weld and Their Conditions
Most welds involve piping, sheets, or beams made of carbon steel, for which a wide range of welding machines are available.
Stainless steel welding requires less intensity but a different arc mode to avoid deformation and splatter, often using a pulsed arc (PULSE) machine.
Aluminum welding, due to its high conductivity, demands high-quality welding current and a pulsed arc mode for thicknesses less than 6 mm.
The thickness of the pieces determines the wire diameter to use:
- Welding: 0.8 – 1.6 mm
- Cladding: 1.2 – 2.4 mm
Choose the welding machine power (Amperes) based on the wire diameter and continuous use time.
Power Categories
- 180-230 A: 220 V/Single-phase, Air-cooled
- 300-350 A: 380 V/Three-phase, Air/Water-cooled
- 400-500 A: 380 V/Three-phase, Water-cooled
- 600 A: 380 V/Three-phase, Water-cooled
Usage Conditions
Workshop Use: Typically powered by 380 V three-phase or 220 V single-phase, where size is not a constraint. Machines with 250 A – 450 A power and high electrical efficiency inverters are preferred.
Workshop MIG Units: May feature a separate feeder with variable connection lengths (5 m to 25 m) for large pieces, avoiding generator manipulation. Sectors like shipbuilding and heavy metalwork may require solutions for lengths up to 50-60 meters.
Field Use: Compact machines with integrated wire coils powered by 220 V single-phase, with limited power (180 – 230 A) for 0.8 – 1 mm wire. More powerful compact machines (up to 350 A) are available for larger pieces.
When using a welding machine on-site, extension cords (25 – 70 m) or generator connections are common. Electrical quality is crucial, with better models offering voltage regulation (+/- 10% typically, +15%/-40% for high-performance units) for constant current, good ignition, and longer equipment lifespan.
Step 3: What budget should be allocated for purchasing a MIG welder?
With the diversity of brands, sellers, and prices, it is often difficult to make a choice and know the right price.
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